A downhole formation testing tool is often used to study flow properties of a formation below the Earth's crust. The downhole formation testing tool is configured to create a flow pulse in the formation and to measure a pressure response of the formation at one or more locations along a wellbore penetrating the porous formation. The flow pulse may be performed using a pump fluidly coupled to the porous formation. The pressure response is often measured with one or more gauges in fluid communication with the porous formation.
When using a known downhole formation testing tool having an extendable probe to create flow pulses, the drawdown pressure generated during, the drawdown is relatively large because of the relatively small flow area between a probe port and the porous formation. Such relatively large drawdown pressure often results in a large amount of electrical power being consumed by the pump. Additionally, pump components may heat during the drawdown. As a result, a duration of the flow pulse may be shortened to prevent failures due to excessive temperatures. Conversely, if the amount of electrical power is limited, the relatively large drawdown pressure results in a relatively low flow rate during the drawdown. In both cases, that is, when flow pulses are shorter or when flow pulses have flow rates of reduced magnitude, pressure responses of the porous formation have also reduced magnitude, or the responses are even undetectable at remote locations.
When an inflatable dual packer testing tool is used to create a flow pulse, the flow area is increased which may alleviate the need for a large amount of electrical power. The inflatable dual packer elements, however, may not be capable of withstanding pressure differences with the wellbore as large as probe seals, and again, the flow rate during flow pulses may have to be limited in magnitude, with similar consequences on the magnitudes of the pressure responses.
Whether using extendable probes, inflatable packers or combinations of extendable probes and inflatable packers, measuring the formation response at locations axially close to each other, such as less than one foot apart which is mostly due to a size of packer elements and/or probe deployment, systems, is often difficult. As a result, characterizing the flow of fluid in the formation near a wall of the wellbore may be difficult which may impact the ability to determine the flow characteristics of the formation [and therefore its economic viability]. Moreover, pressure equilibrium between pressure in a sealed volume, which communicates flow with the porous formation, and pressure in the porous formation near the wall may require a long duration of time to be established. As a result, monitoring the pressure in the porous formation with gauges of known downhole formation testing tools is difficult or unachievable.